1. Field of the Invention
The present invention relates to velocity control of a moving body including a support member, at least one ground-contacting element, and a control loop. The support member supports a subject including an occupant. The ground-contacting element is attached to the support member. The control loop adjusts torque applied to the ground-contacting element so as to allow the moving body to travel while keeping an inverted state of the support member.
2. Description of Related Art
A moving body that includes a support member, at least one ground-contacting element, and a control loop has been known. The support member supports a subject including an occupant. The ground-contacting element is attached to the support member. The control loop adjusts torque applied to the ground-contacting element so as to allow the moving body to travel while keeping an inverted state of the support member. Such a moving body is called inverted pendulum type moving body, since it exercises inverted pendulum control to keep the support member inverted. Hereinafter, the term “moving body” means inverted pendulum type moving body unless otherwise specified. For example, for any moving body travelling with two wheels arranged in parallel, the wheels correspond to the ground-contacting element, and the vehicle body on which an occupant can mount corresponds to the support member.
Japanese Patent No. 3722493 discloses a technique that relates to velocity limiting control of a moving body. According to this technique, a control loop determines torque applied to a ground-contacting element according to an inclination angle (hereinafter referred to as pitch angle) of a support member in a front-back direction (pitch direction) or a temporal differentiation of the inclination angle and a correction value of the pitch angle. The control loop transits to a velocity limiting mode when the velocity of the moving body exceeds a certain value. In the velocity limiting mode, the control loop controls the moving body to apply additional torque to the ground-contacting element by applying the correction'value of the pitch angle. For example, when the moving body travels forwardly, the additional torque is applied to the ground-contacting element. Then, the supporting member is inclined backwardly and the pitch angle is returned to its original value. Hence, the torque determined by the following control loop is decreased, thereby limiting further increase in the vehicle velocity.